Rust inhibited extreme pressure grease



United States Patent 3,390,081 RUST INHIBITED EXTREME PRESSURE GREASE Peter E. Floeck, Anaheim, Calif., assignor to Atlantic Richfield Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Continuation-impart of application Ser. No. 330,608, Dec. 16, 1963. This application Mar. 10, 1967, Ser. No. 622,063

7 Claims. (Cl. 25232.7)

ABSTRACT OF THE DISCLOSURE This application is directed to a grease showing improved physical properties, particularly dropping point, eifected by the synergistic combination of a zinc alkyl dithiophosphate with an imidazoline salt of a fatty acid, such as caprylic acid.

This application is a continuation-in-part application of SN. 330,608, filed Dec. 16, 1963 and now abandoned.

This invention relates to a grease composition and, more particularly, relates to a rust inhibited extreme pressure grease with improved physical properties.

A grease for use in lubricating heavily loaded bearings which are exposed to high humidity and water would normally be a high quality grease containing extreme pressure additives together with a rust inhibitor. The addition of extreme pressure additives to grease compositions has heretofore been known to reduce the dropping point of the grease. The present invention involves a rust inhibited extreme pressure grease composition in which the dropping point is substantially increased over the same grease composition not employing an extreme pressure additive. While the dropping point is increased in the rust inhibited extreme pressure grease of my present invention, the bleeding is reduced and the mechanical stability increased.

It is, therefore, an object of the present invention to provide a rust inhibiting additive for an extreme pressure grease which results in an improvement in the dropping point of a rust inhibited extreme pressure grease.

It is also an object of the present invention to provide a rust inhibitor for an extreme pressure grease which reduces the bleeding characteristics and increases the mechanical stability of the resulting grease.

Other objects and a more complete understanding of my present invention will become apparent from the following description of the invention taken in conjunction with the appended claims.

We have found that a grease composition formulated by using a particular rust inhibitor with an additive which has been found useful as an extreme pressure additive produces a synergism which significantly increases the dropping point of the formulated grease. The rust inhibitor additive used to produce a synergism with one extreme pressure additive is an imidazoline salt of a fatty acid. The compound found useful as an extreme pressure agent and capable of producing the synergism with the imidazoline is a zinc alkyl dithiophosphate.

The base oil and thickening agent utilized in the grease composition of my present invention may be of the conventional type. For example, pale oils, mid-continent solvent treated paraffin base oils, western solvent treated, western refined naphthenic oils, refined Pennsylvania 100% parafiin oils, or mixtures thereof, may be utilized as base oils. The thickening agent utilized in any present grease composition may be a soap of a monocarboxylic acid having from about 14 to 22 carbon atoms per molecule, for example, lauric, myristic, palmitic, oleic, stearic,

ice

hydroxystearic, l2-hydroxystearic methyl esters of 12-hydroxystearic acid, ethyl hexoic, behenic, etc. or their gly cerides, or fatty materials containing such acids or their glycerides. The fatty materials can be vegetable, marine and animal fatty oils and hydrogenated products thereof within the above description. Hydrogenated castor oil, tallow, tallow fatty acids, cottonseed oil, steer-in and hydrogenated fish oils are examples of suitable fatty oils. The metal component of the soap may be an alkali or alkaline earth metal such as lithium, sodium, barium, or mixtures thereof. The preferred soap thickening agents, however, are lithium 12-hydroxystearate, lithium stearate and lithium and barium soaps of C through C monocarboxylic acids or their glycerides. The amount of soap present in the grease of my present invention varies from about 5 to 25% -of the grease by weight, preferably about 5 to 14% by weight, although normally 5 to 6% average.

The greases of my present invention may be prepared by any conventional process, however, preferably the soaps are prepared in situ in the presence of at least a portion of the total oil, preferably about 10% of the total oil. Maximum temperatures of about 230 to 425 F. may be used with a maximum processing temperature of about 230 to 350 F. being preferred to form the proper physical characteristics of the soap fibril. Complete saponifica- .tion usually takes place in about 15 to 20 minutes after maximum temperature is obtained.

For example, the fatty materials and starting oil may be heated in .a kettle until a substantially complete solution is formed. A hot solution of a metal hydroxide such as lithium hydroxide may then be added to the kettle mixture agitated vigorously while the mixture is heated slowly to evaporate water. During the saponification and the dehydration further quantities of the starting oil may be added to limit foaming and maintain the mixture in at least a semifiuid state. After the Water of reaction and the water in which the hydroxide was dissolved is eliminated by evaporation, it is advantageous to raise the temperature of the mixture to about 230 to 350 F. for a period of about 1 to 2 hours. At the end of this period the grease is allowed to cool and cooling may be facilitated by the further addition of base oil. The grease additives such as extreme pressure agents, oxidation inhibitors and rust inhibitors may then be added and the grease milled in the usual manner, for instance in a colloid mill at a clearance of about .001 to .005".

The rust inhibitors useful in my present invention which gives the synergism with the extreme pressure additive are reaction products of an imidazoline with a fatty acid having a carbon chain length of about 5 to 22 carbon atoms. Examples of such fatty acids are caproic, caprylic, capric, lauric, palmitic, stearic and oleic acid. Examples of the imidazolines useful in producing a rust inhibitor useful in my present invention are shown by the following forwhere n is an integer of from 1 to 4 and R and R are selected from group consisting of hydrogen and aliphatic hydrocarbon having from about 5 to 17 carbon atoms.

The imidazolines useful for making the irnidazoline salt of my present invention may be prepared by the reaction of a fatty acid with polyamine, for example, the ethylene polyamines, such as ethylene diamine, diethylene triamine, diethylene tetraamine pentamine, etc. at temperatures of about 500 to 570 F. these imidazolines are of a cyclic tertiary amine type, either the monoarnine or the diamine.

Rust inhibitor additives useful in my present invention are described more fully in my copending application Ser. No. 147,486, filed Oct. 25, 1961 and now abandoned. These additives are elfective in amounts of about 0.75 to 20%, preferably about 1% of the grease by weight for the imidazoline salt and about 1% by weight of the zinc dithiophosphate. For example, the type of imidazolines useful in my present invention may be of the type shown by the following formula:

which are respectively l-(amino ethyl)-2-all yl-2-irnidazoline and 1(2-hydroxy ethyl)-2-n-alkyl-2- imidazoline, and 1-alkyl-2-n-alkyl-2-imidazoline, where the alkyl substitutents are aliphatic hydrocarbons having from about 5 to 17 carbon atoms, such as, for example, pentyl, nonyl, tridecyl, heptadecenyl, hendecenyl, heptadecyl, heptndecenyl, heptacedadienyl, coco, pentadecenyl, etc, derived from relatively long-chain fatty acid materials, such as oleic and tall oil fatty acids, etc.

The reaction product of the fatty acid and the substituted imidazoline in the case of the amine substituted imidazoline may be represented as follows:

(CI'Iz).-.NH OilR (CI'I2);.NH3OCR1 and in the case of the hydroxylated imidazoline is as follows:

(C Hz) [1 O 11 where n is an integer of from 1 to 4 and R, R and R are selected from the group consisting of hydrogen and an aliphatic hydrocarbon having a carbon chain length of from about 4 to 21 carbon atoms.

The latter compound is available commercially as Nalcamines G1l from the Nalco Chemical Company. The amine substituted imidazolines are available commercially as Nalcamines G39M from Nalco Chemical Company, and as Cationic N-FD available from the Leyda Oil and Chemical Company of Hawthorne, Calif.

The Zinc alkyl dithiophosphates used in my present invention are conventionally used as an oxidation inhibitor in motor oils and also has been useful as antiwear antiscufling additives. It has been found that these additives are useful as extreme pressure agents in greases and when used with the rust inhibitors mentioned above impart improved dropping point, bleeding and mechanical stability properties to the grease. An example of a suitable zinc alkyl dithiophosphates useful in the synergistic combination of my present invention is the zinc di (alkyl dithiophosphate) sold by the Lubrizol Corporation as Lubrizol 1395 and identified by the structural formula:

at C. of 1539.6 centistoke and a specific gravity of 1.1684.

My present invention will be described further in conjunction with the following specific examples which are given merely by way of illustration and should not be construed as limiting the invention to the details thereof.

EXAMPLE 1 385 grams of hydrogenated castor oil and 67.94 grams of hydrogenated fish fatty acids (Hy Fae 430) were melted in a grease kettle and 679 grams of western refined naphthenic oil having a viscosity of 70 SUS at 210 F. (W670) added to the kettle to dissolve the melted fats. The mixture was heated to about 195 F. and stirred until the solution was accomplished. 92 grams of 55.11% LiOH (aqueous solution) was heated to 197 F. and added to the kettle and the mixture thickened. 3171 grams of oil was then added to the thickened mass and the temperature raised to about 350 F. The mixture was cooked for an hour and seventeen minutes until the grease mass was substantially completely dehydrated. 3487 grams of finishing oil was added to the kettle and 74.3 grams of zinc dithiophosphate (Lubrizol 1395), 74.3 grams of chlorinated paraffin HV, 74.3 grams of an imidazoline salt of caprylic acid, and 297.3 grams of sulfurized sperm oil were added and the mixture milled at .001" at 162 F. in a Charlotte Colloid Mill. The grease was tested and found to have a penetration at 77 F. of 314, unworked,

and an ASTM of 302. The grease was returned to the kettle and 3.9 grams zinc dithiophosphate (Lubrizol 1395), 3.9 grams chlorinated paraffin HV, 3.9 grams of the imidazoline salt of caprylic acid and 15.7 grams of sulfurized sperm oil were added to the grease and the grease again milled at .001" clearance at F. The unworked penetration at 77 F. was 305 and the ASTM 296. Addi tional oil and additives were added to bring the additive composition to the total shown in Table I and the grease milled again at .001 clearance at 170 F.

TABLE I Composition Grains Wt. percent (Formulation Batch 276-28-(3581) Lithium 12- Hydroxystearate Soap. 376. 62 4. 48 Lithium-Hy Fee 430 Soap. 09. 34 0. 82 W6-70 Base Oil 7, 375). 10 87. 70 Zinc Alkyl Dithiophosphate (Lubrizol 1395) 84. 20 1. (10 Chlorinated Paratfin HV 84. 20 1.00 Sulfurized Sperm Oil (9% S) 330. 60 4. 00 Bust Inhibitor RI 152-59 (imidazoline) salt of eaprylic acid) 84. 20 1.00

Inspection tests Unworked penetration at 77 F 309 ASTM penetration at 7 7 F 303 ASTM dropping point F 459 Shear stability, 4 hour Shell roll test, penetration change percent +6.6 Timken test at 35 lbs. Pass Copper corrosion test, 24 hours at 212 F 1B ASTM D 174360T rust test Pass Alkalinity as LiOH, wt. percent 0.031

EXAMPLE 2 A grease made according to the procedure of Example 1, having essentially the same composition was prepared Without incorporating therein an imidazoline salt additive. Thedata obtained from inspection tests made on the finished grease is shown in Table 11.

TABLE 11' Extreme pressure grease Wt. percent (Formulation batch 2554-6526) lithium 12-hydroxystearate soap 5.21 Lithium-Neo-fat 16-54 soap 0.29 W6-7O base oil 88.50

Zinc alkyl ditniophosphate (Lubrizol 1395) 1.00 Chlorinated parafiin HV 1.00 Sulfurized sperm oil (9% S) 4.00

p j Inspection tests ASTM penetration at 77 F ASTM dropping point F 374 Shear stability, 4 hour Shell roll test, penetration change percent +1392 Timken test at 35 lbs. Pass .ASTM D 1743-60T rust test Fail Alkalinity as LiOH, wt. percent I- 0.052

water were added to the kettle and heated (from a starting temperature of about 190 F.) while agitating the mixturepOil was gradually added as the temperature of the mixture was gradually raised to about 350 F. until saponification was-complete. I

The .sapinification was complete and the grease mass substantially completely dehydrated in about 1 hour and 44 minutes at a temperature of 350 F. The temperature was maintained at 350 F. for about 30 minutes. The grease was cooled by adding oil to a total of 9695 grams and at 185 F., 440.8 grams of sulfurized sperm oil, 110.2 grams of chlorinated paraffin HV and 110.2 grams of the imidazoline salt of caprylic acid (RI 152-59) were added to the mass and thoroughly mixed for about 28 minutes. The grease was then colloidally milled in a Charlotte Mill at .003 clearance at 185 F. The resulting grease was then tested, the significant results of which are included in Table III.

TABLE III Composition (Formulation Batch 56743) Lithium-12 E37- Grams Wt. percent droxystearate Soap 626. 58 5. 69 Lithium-Neofat 16-54 Soap 34. 46 0.31 WG-70 Base Oil 9, 695. 00 88. 00 Chlorinated Paraffin HV... 110. 20 1. 00 Sulfurized Sperm Oil (9% S) 440. 80 400 Rust Inhibitor RI 152-59 idazoline salt of caprylic acid) 110. 20 l. 00

Inspection tests Unworked penetration at 77 F. 324 ASTM penetration at 77 F. 318 ASTM dropping point F 387 EXAMPLE 4 Another grease was prepared according to the procedure of Example 1 incorporating the zinc dithiophosphate and imidazoline salt additives by mixing into the grease at 160 to 170 F. after the addition of the finish oil just before milling at 135 to 144 F. The composition of the grease and the data obtained as a result of tests made on the finished grease are shown in Table IV.

TABLE IV Rust inhibited E.P. grease Wt. percent (Formulation batch 276--6577) lithium 12-hydroxystearate soap 5.21 Lithium-Neo-Fat 16-54 soap 0.29 W6-70 base oil 87.50

6 EXAMPLE 5 A grease was made according to the procedure of Ex ample 1 wherein 2% lead naphthenate was added as an additive to the composition. The additives of the present invention was not utilized in this grease. The composition and results of tests made on the finished grease are shown in Table V.

TABLE v Composition Wt. percent (Formulation batch 241-22-G-481) lithium-hydrogenated castor oil soap 5.69 Lithium-Neo-Fat 16-54 soap 0.31 W6-70 oil 85.25

Sulfurized sperm oil (9% S) 6.00

Chlorinated paraffin HV 0.75

Lead naphthenate, 25% Pb 2.00

Inspection tests ASTM penetration at 77 F. 321

ASTM dropping point F-.. 364

Shear stability, 4 hour Shell roll test, penetration change percent +l1.72

Timken test at 35 lbs. Pass ASTM D l743-60T rust test Not run EXAMPLE 6 Another grease was made according to the procedure of Example 1 with 2% lead naphthenate and the zinc alkyl dithiophosphate-imidazoline salt additives. The composition and results of test made on the finished grease are shown in Table VI.

TABLE VI Composition Wt. percent Formulation batch 276-53-G590) lithium-hydrogenated castor oil soap 2.78 Lithium-Neo-Fat 16-54 soap 1.94 WG-70 oil 86.38

Timken test 35 lbs. Fail EXAMPLES 7 s Two other greases were prepared according to the procedure of Example 1 incorporating the zinc alkyl dithiophosphate and imidazoline salt additives. The composition of the greases and the results of the inspection tests made on the finished greases are shown in Tables VII and VIII.

TABLE VII Composition Grams Wt. percent (Formulation Batch 276-17-G578) Lithium- Castorwax Soap 317. 93 5. 21

' Lithium Neo-Fat 16-54 Soap 17. 47 0.29

Zinc Alkyl Dithiophosphat 61. 00 1. 00

Chlorinated Paraflin HV 61.00 1. 00

Suliurized Sperm Oil (9% S) 243. 4. 00 Bust Inhibitor RI 152-59 (imidazoline salt of caprylic acid) 76. 20 1. 25

7 Inspection tests Unworked penetration 77 F. 329 ASTM penetration 77 F. 321 ASTM dropping point F 438 4 hour Shell roll test, penetration change percent 0.0 Timken test at 35 lbs. Pass Copper corrosion test, 24 hours 212 F. 1B AST M D 174360T rust test Pass Alkalinity a LiOH "percent" 0.032 AAR bleed test, bleed do 1.3 AAR bleed test, evaporation do 1.7

TABLE VIII Composition Grams Wt. percent (Formulation Batch 276-13-G576) Lithium- Castonvax Soap 317. 03 5.21 Lithium-Neoiat 16-54 Soap 17. 47 0. 29 WG-70 011 5, 305.40 87.00 Zinc Alkyl Dithiophosphate 61.00 1.00 Chlorinated Paraffin HV 61. 1. 00 Sulturized Sperm Oil (9% S) 243. 90 4. 00 Rust Inhibitor RI 152-59 (imidazo 111 of caprylic acid) 91.50 1.50

Inspection tests Unworked penetration 77 F. 324 ASTM penetration 77 F. 316 4 hour Shell roll test, penetration change percent 1.2 Tirnken test lbs Fail Copper corrosion test, 24 hours 212 F 1B ASTM D 174360T rust test Pass Alkalinity as LiOH percent 1.108

Examples 2 and 3 show that greases with the rust inhibiting imidazoline salt and the extreme pressure a itive zinc alkyl dithiophosphate incorporated individually but not together in combination as taught by my present invention and shown in Example 1, have a dropping point of approximately 380 F. Similar greases shown in Examples 1 and 4 with the additive ciombination of my present invention show dropping points of 459 F. and 434 F., respectively. This represents a substantial improvement in the base grease attributed to the additive of the present invention and illustrates the synergistic efiect of the two additives in combination. It had previously been found that the extreme pressure additives normally decrease the ASTM dropping point of the grease slightly but when the extreme pressure additive is employed in combination with the imidazoline salt rust inhibitor in accordance with the present invention as above slight increase in the dropping point which clearly indicates that the additive combination of the present invention which was used in Example 6had a substantial beneficial effect on the dropping point of the grease.

An improvement in mechanical stability is obtained by the use of the additive of the present inventionas shown in the results of the tests run on the greases of Examples 4, 7 and 8 where the ASTM penetration change after the 4 hour Shell roll test was +2.95%, 0% l.2%, respectively.

Although I have described my present inventionwith a certain degree of particularity, it is to be understood that the scope of my invention is not to be limited by the details set forth, but should be afforded the full breadth of the appended claims.

I claim:

1. A grease composition comprising a mineral oil of lubricating viscosity, a soap thickening agent in amounts suflicient to gel said lubricating oil to grease consistency, and a synergistic proportion of Zinc dialkyl dithiophosphate and the reaction product of caprylic acid and a imidazoline represented by the formula.

where R is selected from the group consisting of hydrogen and an aliphatic hydrocarbon having from 15 to 17 carbon and n is an integer of at least 1.

2. The composition of claim 1 wherein said imidazoline is 1-(2-aminoethyl)-2n-heptadecyl-2-imidazoline.

3. The composition of claim 1 wherein the caprylic acid-imidazoline reaction product is N on,

H R-o CH2 0 mentioned, a synergistic effect is obtained and the ASTM dropping point is actually increased.

Examples 5 and 6 use a 2% lead naphthenate which is known to cause a lowering of the ASTM dropping point. It should be noted that the dropping point of the grease of Example 6 is slightly improved over that of Example 5 and required less than half the amount of lithium hydrogenated castor oil soap required for thickening the grease of Example 5. Thus, the grease of Example 6, by using about half the amount of this soap, showed a References Cited UNITED STATES PATENTS 2,364,283 12/1944 Frueler 252-327 2,466,517 4/1949 Blair et a1. 252-392 2,991,249 7/1961 Andress et al. 25242.1 3,001,939 9/1961 OHalloran 25232.7

DANIEL E. WYMAN, Primary Examiner.

I. VAUGHN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,390 ,081 June 25 1968 Peter E. Floeck It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 31, "kettle" should read kettle and the line 60, the lower right-hand portion of the formula reading N N I should read 1 R R Column 3, lines 16 and 17, "substitutents" should read substituents I Column 4, TABLE I, second column, line 2 thereof, "69.34 should read 69.35 same table, first column, line 8 thereof, "(imidazoline)" should read (imidazoline Column 5, line 23, "sapinification" should read saponfication same column 5 TABLE III third column, line 5 thereof, "400" should read 4.00.--. Column 7, line 34, "1.108 should read 0.108 line 48, before "grease" insert base Column 8, line 9, "0%-l z%" should read 0% and 1.2% line 31, "carbon" should read carbons lines 36'to 40, that portion of the formula reading HN should read H-lil Columns 7 and 8, the last formula should appear as shown below:

CH3 [CH2] 3-CH-CH2-O- -S-Zn-S- -OCH2-CH- (CH2) 3CH3 H -(l:H-CH C H CH3 CH3 Signed and sealed this 16th day of December 1969..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents 

